Very High Voltage, Heavily Loaded Underground Cables

The problems associated with the use of high-voltage heavily loaded underground cables in Great Britain are reviewed. These installations are becoming necessary because of the rapidly increasing demand for electric energy and where way leaves for overhead lines become impracticable. A major aspect of this situation is the effective control of the thermal environment, which requires that the thermal resistivity of the soil be maintained at as low a value as possible. Details are given of the disappointing results obtained from investigations of the use of sands as a controlled backfill, especially relative to composition and compaction.